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Development of High-Performance X-ray Image Detector as “Eye” of SPring-8 Angstrom Compact Free-Electron Laser (SACLA) Facility (Press Release)

Release Date
15 Mar, 2014
- Realizing high specifications including high radiation tolerance, charge collection without disturbing electric field, high-speed operation, and large-area sensor -

Japan Synchrotron Radiation Research Institute (JASRI)
Institute for Molecular Science, National Institute of Natural Sciences

Key Points
• Functioning as the “eye”of the SACLA facility to obtain data of objects irradiated with SACLA
• Successful development of the X-ray image detector, an essential technology used in SACLA
• One of the World’s highest total performance and greatest stability at X-ray Free-Electron Laser facility realized using the advanced technologies of charge-coupled device (CCD) sensors

RIKEN (Ryoji Noyori, President) and JASRI (Yoshiharu Doi, President) have succeeded in developing an X-ray image detector, the multi-port charge-coupled device (MPCCD) detector, that is optimized for experiments conducted using SACLA,*1 an X-ray free-electron laser (XFEL). An international collaborative research group led by Takaki Hatsui (team leader) of the Data Acquisition Team, Beam Line Research and Development Group, RIKEN SPring-8*3 Center (Tetsuya Ishikawa, Director); Takashi Kameshima (research scientist) of the XFEL Utilization Division, JASRI; Toshio Horigome (section chief) of the Optical Technology Section, Technical Division, Institute for Molecular Science; Hajime Murao (chief enginner) of Meisei Electric Co., Ltd.; David Burt (chief engineer) of e2V, UK; and Andrew Holland (chief technology officer) and Karen Holland (chief executive officer) of XCAM Ltd., UK.
SACLA, an X-ray Free-Electron laser*1, is a powerful tool for analyzing the movement of atoms in a material. In experiments using SACLA, the target sample is irradiated with the generated X-ray laser, and the pattern of the scattered or transmitted X-rays is measured using an X-ray image detector. For the highly precise measurement of the X-ray patterns, 1) high radiation tolerance, 2) efficient charge collection to measure a large number of X-ray photons, 3) precise measurement of all X-ray laser shots of SACLA, and 4) a sensor larger than 100×100 mm2, are required. Until recently, however, such a high-performance X-ray image detector has not been available.
The collaborative research group developed the MPCCD detector that satisfies the above requirements for the high-precision measurement of X-ray patterns utilizing the advanced technologies associated with CCD sensors.*2 With this detector, weak signals from a single photon to strong signals from several thousand photons can be measured simultaneously and precisely using a large-area sensor under severe radiation environment of SACLA. In addition, the detector is operable synchronously with the repetition of SACLA X-ray pulses, enabling the monitoring of real time processes at the speed of atomic motion, and the acquisition of a large volume of data to observe the nanometer scale image. The developed X-ray image detector is an essential technical platform accelerating XFEL science. It is expected that the detector will be used in various experiments using the XFEL as a primary data acquisition apparatus to explore new fields of research opened up by the XFEL.

This research was partially supported by the X-ray Free-Electron Laser Priority Strategy Program, Ministry of Education, Culture, Sports, Science and Technology. The results of this study were published online in the American scientific journal Review of Scientific Instruments on 14 March 2014 Vol. 85, Article number 033110.

"Development of an X-ray Pixel Detector with Multi-port Charge-Coupled Device for X-ray Free-Electron Laser Experiments"
Takashi Kameshima, Shun Ono, Togo Kudo, Kyosuke Ozaki, Yoichi Kirihara, Kazuo Kobayashi, Yuichi Inubushi, Makina Yabashi, Toshio Horigome, Andrew Holland, Karen Holland, David Burt, Hajime Murao, and Takaki Hatsui
Review of Scientific Instruments, 2014

Fig. 1	Developed MPCCD detector for X-ray imaging
Fig. 1 Developed MPCCD detector for X-ray imaging

(Upper) Example of X-ray image detector with a CCD sensor. This is cooled to approximately -20℃ in vacuum for use in the experiment.
(Lower) Multiport detector with eight CCD sensors to realize a large-area image region. The sensors can be arranged with a gap between image area of 0.3 mm and can detect emitted X-rays without deteriorating the performance of sensors.

Fig. 2	Protein structure analysis experiment using developed X-ray image detector
Fig. 2 Protein structure analysis experiment using developed X-ray image detector

(Upper) Schematic of protein structure analysis experiment
(Middle) Equipment used in experiment
(Lower) Data of protein structure obtained in experiment (under analysis)

*1 X-ray free-electron laser (XFEL), SACLA

SACLA is the most compact X-ray Free Electron Laser (XFEL) facility in the world, and is also now the only XFEL operating below 1 Å wavelength. SACLA was built jointly by RIKEN and JASRI as one of the Key Technologies of National Importance, and was completed in March 2011. SACLA's benefits include short wavelength and pulse-width, enabling the observation of living organisms and materials at the atomic level. Significantly, the close proximity between SACLA and the large synchrotron radiation facility SPring-8 enables collaborative projects using both XFEL and bright SR.

*2 Charge-coupled device (CCD) sensor
A CCD sensor consists of a conversion unit that converts X-rays and visible light into electric charges and a structural unit to transfer the generated electric charges. The latter unit has a metal-insulator-semiconductor (MIS) structure.*4

*3 SPring-8
A large synchrotron radiation facility that generates the highest-quality synchrotron radiation, located in Hyogo prefecture, Japan. Owned by Riken, and operated by JASRI. The nickname SPring-8 is short for Super Photon ring-8 GeV. Synchrotron radiation refers to the strong and highly oriented electron magnetic waves generated when the orbit of electrons, accelerated to a near-light speed, is bent by magnetic field. Applications of the synchrotron radiation produced by SPring-8 includes nanotechnology, biotechnology and industrial use.

*4 Metal-insulator-semiconductor (MIS) structure
The MIS structure consists of a semiconductor layer, an insulator layer, and a metal layer, from the bottom. In a CCD sensor, signal charges trapped in the semiconductor layer are moved by changing the voltage applied to the metal layer. Silicon oxide used as the insulator layer is charged by X-ray irradiation, disturbing the operation of the CCD sensor. By adopting a “radiation hard”structure that minimizes the charging effect, the research group succeeded in developing a detector applicable to XFEL experiments, which had been considered to be impossible with a conventional CCD process.

For more information, please contact:
 Team leader Takaki Hatsui (RIKEN)

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